On April 26, 1986, a catastrophic blast blew the lid off Chernobyl’s Reactor No. 4. The explosion was 400 times more potent than the Hiroshima bomb, igniting fires that burned for 10 days, and sending a radioactive cloud across Europe. In the aftermath, ill-equipped workers heroically sealed the smoldering reactor in a concrete sarcophagus, but the hastily constructed shelter was only built to last 30 years.

Now, 30 countries including the UK, France, and the United States have come together to pay for an international rescue plan to build a mighty 25,000-ton steel shelter which will entomb the radiation and last for a century. Building Chernobyl’s Mega Tomb follows the team of international engineers as they race against time to build the structure over the disaster site.